Lasers have become useful in a number of applications. For example, lasers may be used in optical communications to transmit digital data across a fiber-optic network. Directly modulated lasers (DMLs) may be modulated by a modulation signal, such as an electronic digital signal, to produce an optical signal transmitted on a fiber-optic cable. An optically sensitive device, such as a photodiode, is used to convert the optical signal to an electronic digital signal transmitted through the fiber-optic network. Such fiber-optic networks enable modern computing devices to communicate at high speeds and over long distances.
In fiber-optic networks, DMLs are typically implemented as directly modulated distributed feedback (DFB) lasers. Direct amplitude modulation (AM) of DFB lasers and other semiconductor lasers also results in frequency modulation (FM) of the DFB. At high-speeds, e.g., data rates over 10 gigabits per second (G), The FM component of a high-speed optical signal generated by a DFB laser closes the eye after transmission through dispersive fiber such that the reach of a 10 G DFB laser is typically limited to about 5-10 kilometers (km).
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced.